Vinyl chloride polymers containing zinc tungstate

ABSTRACT

Vinyl chloride polymers are compounded with zinc tungstate to provide improved flame resistance and reduce smoke production.

United States Patent 1 [111 3,901,850

Kurtz Aug. 26, 1975 [54] VINYL CHLORIDE POLYMERS 1,852,998 4/l932 Ellisc l l7/l37 CONTAINING ZINC TUNGSTATE 2,610,920 9/1952 Hopkinson260/45.75 3,560,44l 2/l97l Schwarcz et al I. 260/4515 [75] Inventor:Donald M. Kurtz, Akron, Ohio 7 A Th B F Good h C OTHER PUBLICATIONS l 3]Sslgnee' i 6 flmpany The Chemistry and Uses of Fire Retardants by Lyons,

Wiley lnterscience, pp. 112 & I58, 1972. I Fild1 g- 1,1974 HameproofingTextile Fabrics by Little pp. 217 to Appl. No; 493,722

Relerences Cited UNITED STATES PATENTS l2/l926 Eichcngrun ll7/I38 222.Reinhold Pub. Co., 1947.

Primary ExaminerV. P. Hoke Attorney, Agent, or Firm.l. Hughes Powell,Jr.

ABSTRACT Vinyl chloride polymers are compounded with zinc tungstate toprovide improved flame resistance and reduce smoke production.

4 Claims, No Drawings VINYL CHLORIDE POLYMERS CONTAINING ZINC TUNGSTATEBACKGROUND OF THE INVENTION Presently there is a pressing need forimproved plastic products which are safer in fire situations, even forvinyl chloride polymers which generally are considered to be flameresistant. While rigid vinyl chloride products have many structuralapplications useful in buildings and transportation vehicles, many usesare also made of plastieizcd vinyl chloride polymers as in fab ries,upholstery. wall coverings and the like where flame resistance and smokeformation could be a problem. Government and safety regulations relatingto such materials are now in effect. Not only is flame resistance to bereduced in such materials as vinyl chloride plastic products, but smokegenerated by vinyl chloride polymer products in fires also must bereduced. The NBS smoke chamber is accepted as a measure of smokegenerated. Charring is also desired to decrease flame spread. While anumber of materials have been proposed and used in vinyl chloride forthis purpose, very few have been found to be completely satisfactory.Many are not compatible or readily mixed with vinyl chloride polymers,many are colored or form colored products in vinyl chloride polymercompositions and many have adverse effects on the physical properties ofvinyl chloride polymers.

SUMMARY OF THE INVENTION Zinc tungstate is a very effective fire andsmoke retardant in vinyl chloride polymer compositions even in lowconcentrations. The zinc compound is compatible and easily mixed withvinyl chloride polymers in both rigid and flexible forms, has lowtinting power, does not form objectionable color products in vinylchloride polymers and has no adverse effects on the physical propertiesor processing of compounds containing it.

DETAILED DESCRIPTION The zinc tungstate is normally used in powder formin amounts greater than about 0.0l part per I weight parts of vinylchloride polymer, more preferably from about 0.1 to about 5 to weightparts per I00 weight parts of vinyl chloride polymer. From about 0.25 toabout 3 weight parts is a very practical range providing a good balanceof desirable properties in the compounds. The zinc tungstate is readilymixed with the vinyl chloride polymers in powder form as is any otherpowder ingredient mixed with vinyl chloride polymers as is well known tothose skilled in the art.

The vinyl chloride polymers include those vinyl chloatoms, acrylicacids. amides and nitriles thercofsuch as acrylic acid, ethaerylic acid,acrylamides. N-methylol mcthacrylamide. acrylonitrile, methacrylonitrileand the like, alpha-olefins containing 2 to 6 carbon atoms such asethylene and propylene, vinyl esters such as vinyl acetate, vinylbutyrate, vinyl benzoate, vinyl aro matics such as styrene,chlorostyrene, ethyl styrene. vinyl naphthalene. vinyl alkyl ethers,vinyl ketones, chlorinated vinyl chloride polymers; and blends of vinylchloride polymers with other polymers, both plastics and elastomers. forexample, with ABS resins, with 10 to 40% of copolymers of styrene andacrylonitrile or styrene and methyl methacrylate wherein styrene is themajor component, elastomers containing about equal amounts of styreneand acrylonitrile with butadiene. polyurethanes. nitrile elastomers,both liquid and solid containing from about 15 to 40% acrylonitrile withthe remainder butadiene, polyolefins and the like. These vinyl chloridepolymers normally are high molecular weight polymers having a specificviscosity greater than 0.4 measured as a 0.4% solution in nitrobenzene.

The vinyl chloride polymers will be mixed with standard compoundingingredients known to those skilled in the art, pigments, plasticizers,lubricants, stabilizers, fillers, colorants, processing aids, otherflame and smoke retardants, and the like. While these compounds are mosteffective in vinyl chloride polymers substantially free of plasticizerssubject to burning, they also provide improved compositions as to flamepropagation and smoke when plasticizers are present.

In the following Examples, there is reported the oxygen index, Ol, a D'smoke rating and D,,,, a maximum optical density observed with avertical light path in the National Bureau of Smoke Chamber (NBS). Theoxygen index is determined in accordance with ASTM D2863 test method andD' smoke number measured when this apparatus is modified by the meansdescribed by Dipietro et al., Journal of Flame and Flammability, Volume2, Page 36, I971, i.e., the optical density of the smoke generated whenthe sample is burning at the rate of 0.6 gram/minute. The NBS smokechamber and its use are described by Gross et al in fire test methodsASTM ST? 422, l967, Pages l66-206. The NBS D, smoke numbers reported arein the flaming mode.

EXAMPLE I A vinyl chloride polymer compound was prepared by mixing 100weight parts of polyvinyl chloride, Geon l l0X233, specific viscosity0.38 0.42% in nitrobenzene at 30C., with 2 weight parts of polyethylenehaving a specific gravity of 0.924 g/cc and melt index of 5 g/l0minutes, and the amounts of zinc compounds shown in the data tablebelow. The ingredients were all dry blended, milled at 330F. for 5minutes, press ride polymers that are homopolymers, that is, polyvinylmolded at 350F. for 8 minutes at 320F. 6 X 0.25 X chloride, as well asthose copolymers containing vinyl 0.075 inch test samples were used forthe Oxygen Index chloride and up to about 50%. more usually about 30%and Smoke-OI. 2-7/8 X 2-7/8 X 0.05 inch test samples by weight of atleast one other vinylidene monomer were used for the NBS smoke chamberand the 72 char containing at least one terminal CH =C group such formedwas on.% X 54 X 0.075 inch or dry pressed A X as vinylidene chloride,alkyl acrylates and methacry- 36, X 0.280 inch pellets. A minute burnwas used. lates wherein the alkyl group contains 1 to [0 carbon TABLE Ia Zn Zinc Salt in Oxygen A Z lphrl Recipe Index D' D,,."" Chart" 'I'CNone 42 550 630 2 5 z mo, (vs) .22 as 755 2.7 6

TABLE I- continued 'fi Zn Zinc Salt in Oxygen A '1 (phr) Recipe Index D'J'" l),,, Chafl TC'" ZnTi();,"" b) .lli 66 I45 38 lt45 I32 30 ZnWO; (Va).H) 50 265 H11 27 ""Al 55 1K5 322 17.5 40

" D is the smoke rating for the Smoke-l test D,, is the smoke rating forthe NBS Smoke Chamber test All numbers are based on an average ofduplicate runs. Sample thickness was nurmali/ictl to 50 mils '7: Chair MMilM X 100. where M initial wt.. M I final wt. Samples were exposed to apropane torch for l.() minute, Sample geometry was V4" X X0075". Averageof two runs.

"" Cl TC l of theoretical char Char/A. where A is the maximum amount ofchar that can he formed and is defined by 444 X 4 A 100 m X peradditive.

(e) 4 pressed sheet ultcr test was black. Sheet containing ZnWO wasanther.

2. A composition of claim I wherein the vinyl chloride polymer ispoly(vinyl chloride).

3. A composition of claim I wherein the vinyl chloride polymer containsup to about 50% by weight of at least one vinylidene compoundcopolymcrizcd therewith having a terminal CH- ,=C group.

4. A composition of claim 2 wherein there is 0.75 to 3 parts of zinctungstatc.

* =l k k

1. A COMPOSITION COMPRISING A VINYL CHLORIDE POLYMER AND ZINC TUNGSTATEPRESENT IN AMOUNTS FROM ABOUT 0.01 TO ABOUT 10 WEIGHT PARTS OF VINYLCHLORIDE POLYMER.
 2. A composition of claim 1 wherein the vinyl chloridepolymer is poly(vinyl chloride).
 3. A composition of claim 1 wherein thevinyl chloride polymer contains up to about 50% by weight of at leastone vinylidene compound copolymerized therewith having a terminal CH2 C< group.
 4. A composition of claim 2 wherein there is 0.75 to 3 parts ofzinc tungstate.